1. Field of the Invention
The present invention generally relates to control systems for automotive vehicles, and more particularly relates to a haptic braking system of a vehicle in an active cruise control mode.
2. Description of the Related Art
Cruise control systems known in the art enable a driver of a vehicle to set a target vehicle speed. While such systems allow the driver to be less active in driving the vehicle, the driver must be aware of any potential rear end collision with any preceding vehicle. As such, there also exists technology in the art for providing a collision warning to the driver during an active cruise control mode. This technology includes visual indicators, tactile indicators, and audio indicators that are all designed to immediately notify the driver of a potential collision into a rear end of any preceding vehicle. Consequently, the driver has an opportunity to timely utilize a braking system of the vehicle as needed to avoid the collision. Recently, human factor research has indicated that one or more brake pulses may offer a better solution for notifying the driver of the potential collision. The automotive industry is therefore striving to incorporate haptic braking into a cruise control system of an automobile vehicle.
One form of the present invention is a haptic braking method. First, a signal indicative of a request to decelerate a wheel in a haptic manner is received. Second, brake fluid is applied to a brake adjacent the wheel in response to the signal. Third, a pressure level of the brake fluid is cyclically varied over at least one cycle.
A second form of the present invention is also a haptic braking method. First, a signal indicative of a request to decelerate a wheel in a haptic manner is received. Second, in response to the signal, a pump is operated to apply a brake fluid to a brake adjacent the wheel. Third, a valve is operated to cyclically vary a pressure level of the brake fluid over at least one cycle.
A third form of the present invention is a haptic braking system comprising a controller, a pump, and a valve. The controller is operable to provide control signals in response to a signal indicative of a request to decelerate a wheel in a haptic manner. In response to a first control signal, the pump is operable to apply a brake fluid to a brake adjacent the wheel. In response to a second control signal, the valve is operable to cyclically vary a pressure level of the brake fluid over at least one cycle.
A fourth form of the present invention is also a haptic braking system. The system comprises a means for applying a supply of brake fluid to a brake in response to a signal indicating a request to decelerate a wheel in a haptic manner. The system further comprises a means for cyclically varying a pressure level of the brake fluid over at least one cycle.
The foregoing forms, and other forms, features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.